Purpose: When metabolic rate during arm-cranking in the heat is equated between children and adolescents with cerebral palsy (CP) and matched controls (CON), there are no relevant intergroup differences in heat strain. The metabolic rate, however, is known to be higher in CP during treadmill walking. The purpose of this study was to determine if during treadmill walking in the heat, the higher oxygen uptake (V̇O2), and thus greater metabolic heat production in those with CP would result in greater heat strain compared with able-bodied, matched CON.
Methods: Ten boys and girls (10.3–16.3 yr) with spastic CP and 10 individually matched (age, body size, biological maturity, gender, race) healthy CON performed 3 × 10-min treadmill walking bouts in 35°C, 50% RH. Body mass, metabolic variables, heart rate (HR), body temperatures, and rating of perceived exertion (RPE) were periodically measured. Individuals within each CP-CON pair walked at the same speed and slope (0.9 ± 0.4 m·s−1, 3.3 ± 0.6%).
Results: Steady-state V̇O2 during walking, body temperatures, and HR were all higher in the CP group compared with CON. V̇O2 was on average 40% higher, rectal temperature was 0.4°C (99% CI = 0.1–0.6°C) higher and HR (during the final minute of each exercise bout) was 37 beats·min−1 (99% CI = 19–56 beats·min−1) higher. There were no differences between the groups in sweating rate (as inferred from body mass changes corrected for fluid intake and output) or in RPE.
Conclusion: The subjects with CP demonstrated greater thermal strain than CON during treadmill walking where they require more metabolic energy and thus produce more metabolic heat than CON.
1Children’s Exercise and Nutrition Centre, Department of Pediatrics, McMaster University, Hamilton, CANADA; and 2Exercise Science Department, Syracuse University, Syracuse, NY
Address for correspondence: Désirée Maltais, Children’s Exercise and Nutrition Centre, Department of Pediatrics, Chedoke Hospital Division, Hamilton, ON L8N 3Z5, Canada; E-mail: firstname.lastname@example.org.
Submitted for publication February 2004.
Accepted for publication June 2004.
We would like to thank the young people who participated in this study for their time and effort and José Peralta, Brian Timmons, and Mona Zeitoun for their assistance with data collection.